Interlayer for laminated glass, method for producing interlayer for laminated glass, and laminated glass

ABSTRACT

The present invention aims to provide an interlayer film for a laminated glass that enables production of a laminated glass having high visible light transmittance even when deaeration for preliminary pressure bonding and heating for final pressure bonding are performed in parallel in a vacuum deaeration method. The present invention also aims to provide a method for producing the interlayer film for a laminated glass, and a laminated glass including the interlayer film for a laminated glass. Provided is an interlayer film for a laminated glass having a multitude of recesses on at least one surface, the surface with the recesses having a texture aspect ratio Str of 0.04 or lower as measured in conformity with ISO 25178.

TECHNICAL FIELD

The present invention relates to an interlayer film for a laminatedglass that enables production of a laminated glass having high visiblelight transmittance even when deaeration for preliminary pressurebonding and heating for final pressure bonding are performed in parallelin a vacuum deaeration method. The present invention also relates to amethod for producing the interlayer film for a laminated glass and alaminated glass including the interlayer film for a laminated glass.

BACKGROUND ART

A laminated glass including two glass plates integrated through aninterlayer film for a laminated glass containing a thermoplastic resinsuch as plasticized polyvinyl butyral is widely used for automotivewindshields and the like.

Such an automotive windshield is, for example, produced by a vacuumdeaeration method using a rubber bag. In the vacuum deaeration method, alaminate including an interlayer film for a laminated glass interposedbetween at least two glass plates is placed in a rubber bag, and vacuumsuctioned for removal of air remaining between the glass plates and theinterlayer film so as to be preliminarily pressure bonded. Then, thelaminate is pressurized with heat, for example, in an autoclave forfinal pressure bonding to provide a laminated glass.

In such a process for producing a laminated glass by the vacuumdeaeration method, deaeration upon stacking a glass plate and aninterlayer film for a laminated glass together is important. Theinterlayer film for a laminated glass therefore commonly has a multitudeof recesses formed on at least one surface for the purpose of ensuringthe deaeration properties in production of a laminated glass. Inparticular, when the recesses each have a groove shape with a continuousbottom (shape of an engraved line) and adjacent recesses in the shape ofengraved lines are regularly formed in parallel to each other, highlyexcellent deaeration properties can be exhibited (for example, PatentLiterature 1).

However, even with the use of an interlayer film for a laminated glasshaving such recesses in the shape of engraved lines, the air may not besufficiently removed, and air bubbles may remain in the resultinglaminated glass, reducing the visible light transmittance. Such areduction in visible light transmittance due to defective deaeration issignificant especially when the deaeration for the preliminary pressurebonding and the heating for the final pressure bonding are performed inparallel in the vacuum deaeration method to shorten the processduration.

CITATION LIST

Patent Literature

-   Patent Literature 1: JP 2001-48599 A

SUMMARY OF INVENTION Technical Problem

The present invention aims to provide an interlayer film for a laminatedglass that enables production of a laminated glass having high visiblelight transmittance even when deaeration for preliminary pressurebonding and heating for final pressure bonding are performed in parallelin a vacuum deaeration method. The present invention also aims toprovide a method for producing the interlayer film for a laminated glassand a laminated glass including the interlayer film for a laminatedglass.

Solution to Problem

The present invention relates to an interlayer film for a laminatedglass having a multitude of recesses on at least one surface, thesurface with the recesses having a texture aspect ratio Str of 0.04 orlower as measured in conformity with ISO 25178.

The present invention is described in detail below.

The present inventors investigated the cause of the reduction in visiblelight transmittance due to defective deaeration in production of alaminated glass by the vacuum deaeration method. In the vacuumdeaeration method, a laminate including an interlayer film for alaminated glass interposed between at least two glass plates is placedin a rubber bag, and vacuum suctioned for removal of air remainingbetween the glass plates and the interlayer film so as to bepreliminarily pressure bonded. The laminate is then pressurized withheat, for example, in an autoclave for final pressure bonding to providea laminated glass. In the case of performing the deaeration for thepreliminary pressure bonding and the heating for the final pressurebonding in parallel to shorten the process duration, the heating crushesthe shape of the recesses, causing a phenomenon called “precedingsealing” in which the layers of the laminate are bonded withoutsufficient deaeration. The present inventors thus found out that thiscauses insufficient deaeration.

The interlayer film for a laminated glass having recesses in the shapeof engraved lines disclosed in Patent Literature 1 allows easy airsuctioning in deaeration, making preceding sealing relatively unlikelyto occur. In the case of shortening the process duration, however, theinterlayer film cannot completely prevent preceding sealing. This ispresumably because the recesses in the shape of engraved lines areuneven in their groove depths and shapes, so that the grooves arelocally blocked, causing preceding sealing.

The present inventors made further intensive studies to find out thatwhen the surface with the recesses of the interlayer film for alaminated glass has a texture aspect ratio Str lower than or equal to acertain value, the interlayer film can prevent preceding sealing andenables production of a laminated glass having high visible lighttransmittance even in the case of performing the deaeration for thepreliminary pressure bonding and the heating for the final pressurebonding in parallel to shorten the process duration. The presentinventors thus completed the present invention.

The interlayer film for a laminated glass of the present invention has amultitude of recesses on at least one surface. This ensures thedeaeration properties in production of a laminated glass. The interlayerfilm for a laminated glass may have the recesses on only one surface,but preferably has the recesses on both surfaces because the deaerationproperties are markedly improved.

In the interlayer film for a laminated glass of the present invention,the surface with the recesses has a texture aspect ratio Str(hereinafter also referred to simply as “Str”) of 0.04 or lower asmeasured in conformity with ISO 25178.

The Str is an index of the shape regularity. The Str lies between 0and 1. A Str closer to 0 indicates a more regular shape, while a Strcloser to 1 indicates a more irregular shape. In a conventionalinterlayer film for a laminated glass having recesses on a surface, thesurface with the recesses has a Str of 0.1 or higher. In the interlayerfilm for a laminated glass of the present invention, the surface withthe recesses has a Str of 0.04 or lower, or in other words, has far moreregular recesses than before. As a result, the interlayer film for alaminated glass prevents preceding sealing and enables production of alaminated glass having high visible light transmittance even in the caseof performing the deaeration for the preliminary pressure bonding andthe heating for the final pressure bonding in parallel to shorten theprocess duration. This is presumably because with highly regularrecesses, the blockage of grooves due to local crushing of the recessescan be prevented. The surface with the recesses preferably has a Str of0.03 or lower, more preferably 0.015 or lower.

When the Str is measured to the third decimal place, the number of thethird decimal place is taken in consideration to determine if the Str isincluded in the scope of the present invention. Specifically, in theinterlayer film for a laminated glass of the present invention, the Strof the surface with the recesses is 0.040 or lower. For example, a Strof 0.040 is included in the scope of the present invention. A Str of0.041 is out of the scope of the present invention. The same shall applywhen the Str is measured to the fourth decimal place. Specifically, aStr of 0.0400 is included in the scope of the present invention. A Strof 0.0401 is out of the scope of the present invention.

Specifically, the Str can be measured by the following method, forexample.

The surface of the interlayer film for a laminated glass is analyzedusing a three-dimensional white light interference microscope (e.g.,ContourGT-K available from Bruker AXS GmbH) in a 2 mm square field ofview at an objective lens magnification of 50 times, an internal lensmagnification of 0.5 times, and a resolution set to “half resolution” toobtain images. In this operation, the light quantity and threshold areset as appropriate to minimize noise in the analysis. The obtainedimages are subjected to planarization and noise removal processes, andnoise is further removed using a Gaussian filter. Then, the Str value iscalculated by a method specified in ISO 25178.

In the interlayer film for a laminated glass of the present invention,after heating at 100° C. for 15 minutes, the surface with the recessespreferably has a Str of 0.08 or lower. Production of a laminated glassby the vacuum deaeration method includes heating to 90° C. to 100° C. inthe final pressure bonding. When the regularity of the recesses ishigher than or equal to a certain level even after heating to around100° C., even better deaeration properties can be exhibited. The surfacewith the recesses after heating at 100° C. for 15 minutes morepreferably has a Str of 0.05 or lower.

In an interlayer film for a laminated glass containing a thermoplasticresin, an increase in the Str of the surface with the recesses due toheating is unavoidable. The increase, however, is preferably as small aspossible from the standpoint of ensuring the deaeration properties. Inother words, when the increase in the Str value is small even afterheating for a certain time, even better deaeration properties can beexhibited. Specifically, the absolute value ΔStr of the differencebetween the Str values measured before and after heating at 100° C. for15 minutes is preferably 0.1 or less.

The present invention also encompasses an interlayer film for alaminated glass having a multitude of recesses on at least one surface,the surface with the recesses having a ΔStr of 0.1 or less where theΔStr is the absolute value of the difference between the texture aspectratio Str as measured in conformity with ISO 25178 and the textureaspect ratio Str as measured after heating at 100° C. for 15 minutes.

The shape of the recesses is at least a groove shape, and may be anyshape commonly employed for recesses formed on the surface of aninterlayer film for a laminated glass, such as a shape of engraved linesor a lattice. In particular, preferably, the recesses each have a grooveshape with a continuous bottom (shape of an engraved line) (hereinaftersuch recesses are also referred to as “recesses in the shape of engravedlines”) and adjacent recesses are regularly arranged side by side inparallel to each other.

Commonly, easiness of deaeration upon pressure bonding of a laminateincluding an interlayer film for a laminated glass interposed betweentwo glass plates closely relates to the communication properties andsmoothness of the bottoms of the recesses. When the recesses on at leastone surface of the interlayer film have the shape of engraved lines andare regularly arranged side by side in parallel to each other, thecommunication properties of the bottoms are enhanced to remarkablyimprove the deaeration properties.

The state of “regularly arranged side by side” means both a state wherethe adjacent recesses in the shape of engraved lines are arranged sideby side in parallel to each other at equal intervals and a state wherethe adjacent recesses in the shape of engraved lines are arranged sideby side in parallel to each other but the intervals therebetween are notnecessarily equal to each other. FIG. 1 and FIG. 2 are schematic viewseach illustrating an exemplary interlayer film for a laminated glass inwhich recesses each having a groove shape are arranged side by side inparallel to each other at equal intervals.

FIG. 3 is a schematic view illustrating an exemplary interlayer film fora laminated glass in which recesses each having a groove shape arearranged side by side in parallel to each other at unequal intervals. InFIG. 3 , an interval A between a recess 1 and a recess 2 is differentfrom an interval B between a recess 1 and a recess 3. The recesses inthe shape of engraved lines do not necessarily have a groove shape witha completely continuous bottom, and may have a partition wall in a partof the bottom.

The protrusions formed correspondingly to the recesses may have a shapetransferred from an embossing roll. The protrusions may each have a flattop as illustrated in FIG. 1 or a non-flat top as illustrated in FIG. 2. In the case where the protrusions each have a flat top, the flatsurface of the top may further have fine protrusions and recesses formedthereon. Moreover, the protrusions, among the protrusions and recesses,may have the same height or different heights. The recessescorresponding to these protrusions may have the same depth or differentdepths as long as the recesses each have a continuous bottom.

The lower limit of the ten-point average roughness (Rz) of the recessesin the shape of engraved lines is preferably 10 μm and the upper limitthereof is preferably 80 μm. When the roughness (Rz) of the recesses inthe shape of engraved lines is within the range, excellent deaerationproperties can be exhibited. The lower limit of the ten-point averageroughness (Rz) of the recesses in the shape of engraved lines is morepreferably 20 μm, and the upper limit thereof is more preferably 60 μm.The upper limit is still more preferably 50 μm.

The ten-point average roughness (Rz) of the recesses in the shape ofengraved lines as used herein is Rz specified in JIS B 0601(1994), andcan be obtained by measurement in a perpendicular direction so as totransverse the direction in which the recesses in the direction ofengraved lines are continuous. The measurement device may be, forexample, “Surfcorder SE300” available from Kosaka Laboratory Ltd. Themeasurement may be performed at a cut-off value of 2.5 mm, a standardlength of 2.5 mm, a measurement length of 12.5 mm, a spare length of 2.5mm, and a probe feed rate of 0.5 mm/sec, with a probe having a tipradius of 2 μm and a tip angle of 60°. The measurement is performed at23° C. and 30 RH %.

The lower limit of the interval Sm between the adjacent recesses in theshape of engraved lines is preferably 100 μm, and the upper limitthereof is preferably 500 μm. When the interval Sm between the recessesin the shape of engraved lines is within the range, excellent deaerationproperties can be exhibited. The lower limit of the interval Sm betweenthe recesses in the shape of engraved lines is more preferably 160 μm,and the upper limit thereof is more preferably 350 μm. The upper limitis still more preferably 250 μm.

The interval Sm between the recesses in the shape of engraved linesherein can be obtained by observing first and second surfaces(observation range: 20 mm×20 mm) of the interlayer film for a laminatedglass with an optical microscope (“BS-D8000III” available from SonicCorp.) to measure the intervals between adjacent recesses andcalculating the average of the shortest distances between deepestbottoms of the adjacent recesses.

The following describes a specific method for adjusting the Str of thesurface with the recesses to 0.04 or lower in the interlayer film for alaminated glass of the present invention, based on an exemplaryinterlayer film for a laminated glass having the recesses in the shapeof engraved lines on at least one surface.

The method for imparting the recesses in the shape of engraved lines toa surface of the interlayer film for a laminated glass usually includesa first step of imparting fine protrusions and recesses to a surface ofa resin film and a second step of imparting recesses in the shape ofengraved lines to the surface.

Specifically, for example, in the first step, a random pattern ofprotrusions and recesses is transferred to both surfaces of a resin filmusing a pair of embossing rolls in the same shape as a device fortransferring the pattern of protrusions and recesses. The embossingrolls used may be ones having a coarse main embossed pattern and a finesub-embossed pattern produced by a method including forming randomprotrusions and recesses on the surfaces of a pair of iron rolls with anabrasive material, subjecting the iron rolls to vertical grinding, andthen forming finer protrusions and recesses with a finer abrasivematerial on planar portions after the vertical grinding. Alternatively,in the first step, fine protrusions and recesses may be imparted by anextrusion lip embossing method which takes advantage of melt fracture.

In the second step, a pair of rolls including a metal roll having asurface milled with a triangular oblique line-type mill and a rubberroll having a JIS hardness of 65 to 75 is used as a device fortransferring a pattern of protrusions and recesses. The resin film ispassed through this device for transferring a pattern of protrusions andrecesses to impart, to one surface of the resin film, protrusions andrecesses in which recesses each have a groove shape with a continuousbottom (shape of an engraved line) and are arranged side by side inparallel to each other at equal intervals.

In order to adjust the Str of the surface with the recesses of theinterlayer film for a laminated glass to 0.04 or lower, it is importantthat the resin film after the first step has an arithmetic averageroughness Ra of 4 μm or less as measured in conformity with JIS B0601(1994) (Condition 1). It is also important that in the second step,the linear velocity when the recesses in the shape of engraved lines areimparted to the resin film (when the resin film is passed through thedevice for transferring a pattern of protrusions and recesses) is 10m/min or less (Condition 2).

In the first step, the fine protrusions and recesses are preferablyimparted such that the arithmetic average roughness Ra is 1 μm orgreater so as to prevent blocking in stacking the interlayer films for alaminated glass. At this time, when the arithmetic average roughness Raof the fine protrusions and recesses is 4 μm or less, the surface withthe recesses of the resulting interlayer film for a laminated glass canhave a Str of 0.04 or lower. The arithmetic average roughness Ra of theresin film after the first step is preferably 2 μm or less.

The product (Ra×Sm) of the arithmetic average roughness Ra of the resinfilm after the first step as measured in conformity with JIS B0601(1994) and the interval Sm between the recesses is preferably 2,500or less. When the product (Ra×Sm) is 2,500 or less, the surface with therecesses can more reliably have a Str of 0.04 or lower.

In the second step, the resin film is passed through the device fortransferring a pattern of protrusions and recesses to have the recessesin the shape of engraved lines. When the linear velocity in passing theresin film through the device for transferring a pattern of protrusionsand recesses is 10 m/min or less, in other words, when the recesses inthe shape of engraved lines are slowly shaped, the surface with therecesses of the resulting interlayer film for a laminated glass can havea Str of 0.04 or lower. The linear velocity in the second step ispreferably 5 m/min or less.

The interlayer film for a laminated glass of the present inventionpreferably contains a thermoplastic resin.

Examples of the thermoplastic resin include polyvinylidene fluoride,polytetrafluoroethylene, vinylidene fluoride-propylene hexafluoridecopolymers, polytrifluoroethylene, acrylonitrile-butadiene-styrenecopolymers, polyesters, polyethers, polyamides, polycarbonates,polyacrylates, polymethacrylates, polyvinyl chloride, polyethylene,polypropylene, polystyrene, polyvinyl acetal, ethylene-vinyl acetatecopolymers, polyoxymethylene (or polyacetal) resins, acetoacetal resins,polyvinyl benzyl acetal resins, and polyvinyl cumine acetal resins. Theinterlayer film for a laminated glass of the present invention containspreferably a polyvinyl acetal or ethylene-vinyl acetate copolymer, morepreferably a polyvinyl acetal.

The polyvinyl acetal may be any polyvinyl acetal obtainable byacetalization of polyvinyl alcohol with an aldehyde. Preferred ispolyvinyl butyral. Two or more types of polyvinyl acetal may be used incombination as needed.

The lower limit of the acetal group content of the polyvinyl acetal ispreferably 40 mol % and the upper limit thereof is preferably 85 mol %.The lower limit is more preferably 60 mol % and the upper limit is morepreferably 75 mol %.

The lower limit of the hydroxy group content of the polyvinyl acetal ispreferably 15 mol % and the upper limit thereof is preferably 40 mol %.With the hydroxy group content of 15 mol % or more, the adhesivenessbetween the interlayer film for a laminated glass and glass is improved.With the hydroxy group content of 40 mol % or less, the handleability ofthe interlayer film for a laminated glass is improved.

The acetal group content and the hydroxy group content can be measuredin conformity with JIS K6728 “Testing methods for polyvinyl butyral”.

The polyvinyl acetal can be prepared by acetalization of polyvinylalcohol with an aldehyde.

The polyvinyl alcohol can be commonly prepared by saponification ofpolyvinyl acetate. Polyvinyl alcohol having a degree of saponificationof 70 to 99.9 mol % is typically used. The degree of saponification ofthe polyvinyl alcohol is preferably 80 to 99.9 mol %.

The lower limit of the degree of polymerization of the polyvinyl alcoholis preferably 500 and the upper limit thereof is preferably 4,000. Whenthe degree of polymerization of the polyvinyl alcohol is 500 or more,the laminated glass to be obtained has higher penetration resistance.When the degree of polymerization of the polyvinyl alcohol is 4,000 orless, formation of the interlayer film for a laminated glass isfacilitated. The lower limit of the degree of polymerization of thepolyvinyl alcohol is more preferably 1,000 and the upper limit thereofis more preferably 3,600.

Any aldehyde may be used, and commonly preferred is a C1-C10 aldehyde.Any C1-C10 aldehyde may be used, and examples thereof includen-butyraldehyde, isobutyraldehyde, n-valeraldehyde,2-ethylbutyraldehyde, n-hexylaldehyde, n-octylaldehyde, n-nonylaldehyde,n-decylaldehyde, formaldehyde, acetaldehyde, benzaldehyde, polyvinylbenzylaldehyde, and polyvinyl cuminaldehyde. In particular,n-butyraldehyde, n-hexylaldehyde, and n-valeraldehyde are preferred, andn-butyraldehyde is more preferred. Each of these aldehydes may be usedalone, or two or more thereof may be used in combination.

The interlayer film for a laminated glass of the present inventionpreferably contains a plasticizer.

Any plasticizer may be used, and examples thereof include organic esterplasticizers such as monobasic organic acid esters and polybasic organicacid esters, and phosphoric acid plasticizers such as organophosphateplasticizers and organophosphite plasticizers. The plasticizer ispreferably a liquid plasticizer.

Any monobasic organic acid ester may be used, and examples thereofinclude glycol esters obtained by a reaction between a glycol and amonobasic organic acid. Examples of the glycol include triethyleneglycol, tetraethylene glycol, and tripropylene glycol. Examples of themonobasic organic acid include butyric acid, isobutyric acid, caproicacid, 2-ethylbutyric acid, heptylic acid, n-octylic acid, 2-ethylhexylicacid, pelargonic acid (or n-nonylic acid), and decylic acid. Inparticular, preferred are triethylene glycol dicaproate, triethyleneglycol-di ethylbutyrate, triethylene glycol-di-n-octylate, andtriethylene glycol-di-2-ethylhexylate.

Any polybasic organic acid ester may be used, and examples thereofinclude ester compounds of a polybasic organic acid (e.g., adipic acid,sebacic acid, and azelaic acid) and a C4-C8 linear or branched alcohol.In particular, preferred are dibutyl sebacate, dioctyl azelate, anddibutyl carbitol adipate.

Any organic ester plasticizer may be used, and examples thereof includetriethylene glycol di-2-ethylbutyrate, triethylene glycoldi-2-ethylhexanoate, triethylene glycol dicaprylate, triethylene glycoldi-n-octanoate, triethylene glycol di-n-heptanoate, tetraethylene glycoldi-n-heptanoate, tetraethylene glycol di-2-ethylhexanoate, dibutylsebacate, dioctyl azelate, dibutyl carbitol adipate, ethylene glycoldi-2-ethylbutyrate, 1,3-propylene glycol di-2-ethylbutyrate,1,4-butylene glycol di-2-ethylbutyrate, diethylene glycoldi-2-ethylbutyrate, diethylene glycol di-2-ethylhexanoate, dipropyleneglycol di-2-ethylbutyrate, triethylene glycol di-2-ethylpentanoate,tetraethylene glycol di-2-ethylbutyrate, diethylene glycol dicaprylate,dihexyl adipate, dioctyl adipate, hexylcyclohexyl adipate, diisononyladipate, heptylnonyl adipate, dibutyl sebacate, oil-modified sebacicalkyds, mixtures of phosphoric acid esters and adipic acid esters,adipic acid esters, mixed type adipic acid esters prepared from C4-C9alkyl alcohols and C4-C9 cyclic alcohols, and C6-C8 adipic acid esterssuch as hexyl adipate.

Any organophosphate plasticizer may be used, and examples thereofinclude tributoxyethyl phosphate, isodecylphenyl phosphate, andtriisopropyl phosphate.

For less hydrolysis, the plasticizer contains preferably triethyleneglycol di-2-ethylhexanoate (3GO), triethylene glycol di-2-ethylbutyrate(3GH), tetraethylene glycol di-2-ethylhexanoate (4GO), or dihexyladipate (DHA), more preferably tetraethylene glycol di-2-ethylhexanoate(4GO) or triethylene glycol di-2-ethylhexanoate (3GO), still morepreferably triethylene glycol di-2-ethylhexanoate.

The amount of the plasticizer in the interlayer film for a laminatedglass of the present invention is not particularly limited. The lowerlimit thereof is preferably 30 parts by weight and the upper limitthereof is preferably 90 parts by weight based on 100 parts by weight ofthe polyvinyl acetal. When the amount of the plasticizer is 30 parts byweight or more, the interlayer film for a laminated glass has a low meltviscosity, improving the deaeration properties in the production of alaminated glass using the interlayer film for a laminated glass. Whenthe amount of the plasticizer is 90 parts by weight or less, thetransparency of the interlayer film for a laminated glass is improved.The lower limit of the amount of the plasticizer is more preferably 35parts by weight and the upper limit thereof is more preferably 70 partsby weight, still more preferably 63 parts by weight.

When the amount of the plasticizer is 55 parts by weight or more,excellent sound insulation properties can be imparted to the interlayerfilm for a laminated glass.

The interlayer film for a laminated glass of the present inventionpreferably contains an adhesion modifier. The adhesion modifiercontained adjusts the adhesion force to glass, resulting in productionof a laminated glass excellent in penetration resistance.

The adhesion modifier used is suitably, for example, at least oneselected from the group consisting of an alkali metal salt, an alkalineearth metal salt, and a magnesium salt. Examples of the adhesionmodifier include salts of potassium, sodium, magnesium, and the like.

Examples of an acid constituting the salts include organic acids such ascarboxylic acids (e.g., octylic acid, hexylic acid, 2-ethylbutyric acid,butyric acid, acetic acid, formic acid) and inorganic acids such ashydrochloric acid and nitric acid.

In the case where the interlayer film for a laminated glass of thepresent invention is required to have heat insulation properties, theinterlayer film for a laminated glass may contain a heat ray absorber.

The heat ray absorber may be any heat ray absorber that can blockinfrared rays. Specifically, preferred is at least one selected from thegroup consisting of tin-doped indium oxide (ITO) particles,antimony-doped tin oxide (ATO) particles, aluminum-doped zinc oxide(AZO) particles, indium-doped zinc oxide (IZO) particles, tin-doped zincoxide particles, silicon-doped zinc oxide particles, cesium-dopedtungsten oxide (CWO) particles, lanthanum hexaboride particles, andcerium hexaboride particles.

In the case where the interlayer film for a laminated glass of thepresent invention is required to have luminescent properties, theinterlayer film for a laminated glass may contain a luminescentmaterial.

The luminescent material may be any luminescent material that can becomeluminous under irradiation with excitation light. Examples thereofinclude lanthanoid complexes having a ligand containing a halogen atomand luminescent materials having a terephthalic acid ester structure.

The interlayer film for a laminated glass of the present invention mayinclude conventional additives such as a UV blocking agent, anantioxidant, a light stabilizer, a modified silicone oil as an adhesionmodifier, a flame retardant, an antistatic agent, a moisture-proofagent, a heat ray reflecting agent, a heat ray absorber, ananti-blocking agent, and a colorant made of a pigment or dye, as needed.

The interlayer film for a laminated glass of the present invention mayhave a single-layer structure or a multilayer structure including aplurality of layers stacked together.

In the case where the interlayer film for a laminated glass of thepresent invention has a multilayer structure, various functions can beimparted to the obtained interlayer film for a laminated glass bycontrolling the components of each of the combined layers.

For example, in order to impart sound insulation properties to theinterlayer film for a laminated glass of the present invention, theamount of the plasticizer (hereafter, also referred to as amount X)relative to 100 parts by weight of the thermoplastic resin in one layermay be controlled to be more than the amount of the plasticizer(hereafter, also referred to as amount Y) relative to 100 parts byweight of the thermoplastic resin in the different layer. In this case,the amount X is more than the amount Y preferably by 5 parts by weightor more, more preferably by 10 parts by weight or more, still morepreferably by 15 parts by weight or more. For allowing the interlayerfilm for a laminated glass to have higher penetration resistance, thedifference between the amount X and the amount Y is preferably 50 partsby weight or less, more preferably 40 parts by weight or less, stillmore preferably 35 parts by weight or less. The difference between theamount X and the amount Y is calculated based on the equation:

(difference between the amount X and the amount Y)=(the amount X−theamount Y).

The lower limit of the amount X is preferably 45 parts by weight and theupper limit thereof is preferably 80 parts by weight. The lower limit ismore preferably 50 parts by weight and the upper limit is morepreferably 75 parts by weight. The lower limit is still more preferably55 parts by weight and the upper limit is still more preferably 70 partsby weight. When the amount X is adjusted to the preferable lower limitor more, high sound insulation properties can be exerted. When theamount X is adjusted to the preferable upper limit or less, theplasticizer can be prevented from bleeding out, so that a reduction inthe transparency or the adhesiveness of the interlayer film for alaminated glass can be prevented.

The lower limit of the amount Y is preferably 20 parts by weight and theupper limit thereof is preferably 45 parts by weight. The lower limit ismore preferably 30 parts by weight and the upper limit is morepreferably 43 parts by weight. The lower limit is still more preferably35 parts by weight and the upper limit is still more preferably 41 partsby weight. When the amount Y is adjusted to the preferable lower limitor more, high penetration resistance can be exerted. When the amount Yis adjusted to the preferable upper limit or less, the plasticizer canbe prevented from bleeding out, so that a reduction in the transparencyor the adhesiveness of the interlayer film for a laminated glass can beprevented.

In order to impart sound insulation properties to the interlayer filmfor a laminated glass of the present invention, the thermoplastic resinin the one layer is preferably a polyvinyl acetal X. The polyvinylacetal X can be prepared by acetalization of polyvinyl alcohol with analdehyde. The polyvinyl alcohol can be commonly prepared bysaponification of polyvinyl acetate. The lower limit of the averagedegree of polymerization of the polyvinyl alcohol is preferably 200 andthe upper limit thereof is preferably 5,000. When the average degree ofpolymerization of the polyvinyl alcohol is 200 or higher, thepenetration resistance of the interlayer film for a laminated glass tobe obtained can be improved. When the average degree of polymerizationof the polyvinyl alcohol is 5,000 or lower, formability of theinterlayer film for a laminated glass can be ensured. The lower limit ofthe average degree of polymerization of the polyvinyl alcohol is morepreferably 500 and the upper limit thereof is more preferably 4,000. Theaverage degree of polymerization of the polyvinyl alcohol is determinedby a method in accordance with “Testing methods for polyvinyl alcohol”in JIS K 6726.

The lower limit of the carbon number of an aldehyde used foracetalization of the polyvinyl alcohol is preferably 4 and the upperlimit thereof is preferably 6. When an aldehyde having 4 or more carbonatoms is used, a sufficient amount of the plasticizer can be stablycontained so that excellent sound insulation properties can be obtained.Moreover, bleeding out of the plasticizer can be prevented. When analdehyde having 6 or less carbon atoms is used, synthesis of thepolyvinyl acetal X is facilitated to ensure the productivity. The C4-C6aldehyde may be a linear or branched aldehyde, and examples thereofinclude n-butyraldehyde and n-valeraldehyde.

The upper limit of the hydroxy group content of the polyvinyl acetal Xis preferably 30 mol %. When the hydroxy group content of the polyvinylacetal X is 30 mol % or less, the plasticizer can be contained in anamount needed for exhibiting sound insulation properties, and bleedingout of the plasticizer can be prevented. The upper limit of the hydroxygroup content of the polyvinyl acetal X is more preferably 28 mol %,still more preferably 26 mol %, particularly preferably 24 mol %, andthe lower limit thereof is preferably 10 mol %, more preferably 15 mol%, still more preferably 20 mol %.

The hydroxy group content of the polyvinyl acetal X is a value inpercentage (mol %) of the mol fraction obtained by dividing the amountof ethylene groups to which hydroxy groups are bonded by the amount ofall the ethylene groups in the main chain. The amount of ethylene groupsto which hydroxy groups are bonded can be determined by measuring theamount of ethylene groups to which hydroxy groups are bonded in thepolyvinyl acetal X by a method in accordance with “Testing methods forpolyvinyl butyral” in JIS K 6728.

The lower limit of the acetal group content of the polyvinyl acetal X ispreferably 60 mol % and the upper limit thereof is preferably 85 mol %.When the acetal group content of the polyvinyl acetal X is 60 mol % ormore, the one layer has higher hydrophobicity and can contain theplasticizer in an amount needed for exhibiting sound insulationproperties, and bleeding out of the plasticizer and whitening can beprevented. When the acetal group content of the polyvinyl acetal X is 85mol % or less, synthesis of the polyvinyl acetal X is facilitated toensure the productivity. The lower limit of the acetal group content ofthe polyvinyl acetal X is more preferably 65 mol %, still morepreferably 68 mol % or more.

The acetal group content can be determined by measuring the amount ofethylene groups to which acetal groups are bonded in the polyvinylacetal X by a method in accordance with “Testing methods for polyvinylbutyral” in JIS K 6728.

The lower limit of the acetyl group content of the polyvinyl acetal X ispreferably 0.1 mol % and the upper limit thereof is preferably 30 mol %.When the acetyl group content of the polyvinyl acetal X is 0.1 mol % ormore, the plasticizer can be contained in an amount needed forexhibiting sound insulation properties, and bleeding out of theplasticizer can be prevented. When the acetyl group content of thepolyvinyl acetal X is 30 mol % or less, the one layer has higherhydrophobicity to prevent whitening. The lower limit of the acetyl groupcontent of the polyvinyl acetal X is more preferably 1 mol %, still morepreferably 5 mol %, particularly preferably 8 mol %, and the upper limitthereof is more preferably 25 mol %, still more preferably 20 mol %.

The acetyl group content is a value in percentage (mol %) of the molfraction obtained by subtracting the amount of ethylene groups to whichacetal groups are bonded and the amount of ethylene groups to whichhydroxy groups are bonded from the amount of all the ethylene groups inthe main chain and dividing the resulting value by the amount of all theethylene groups in the main chain.

The polyvinyl acetal X is preferably a polyvinyl acetal with the acetylgroup content of 8 mol % or more or a polyvinyl acetal with the acetylgroup content of less than 8 mol % and the acetal group content of 65mol % or more. In this case, the one layer can readily contain theplasticizer in an amount needed for exhibiting sound insulationproperties. The polyvinyl acetal X is more preferably a polyvinyl acetalhaving the acetyl group content of 8 mol % or more or a polyvinyl acetalhaving the acetyl group content of less than 8 mol % and the acetalgroup content of 68 mol % or more.

In order to impart sound insulation properties to the interlayer filmfor a laminated glass of the present invention, the thermoplastic resinin the different layer is preferably a polyvinyl acetal Y. The polyvinylacetal Y preferably has a greater hydroxy group content than thepolyvinyl acetal X.

The polyvinyl acetal Y can be prepared by acetalization of polyvinylalcohol with an aldehyde. The polyvinyl alcohol can be commonly obtainedby saponification of polyvinyl acetate. The lower limit of the averagedegree of polymerization of the polyvinyl alcohol is preferably 200 andthe upper limit thereof is preferably 5,000. When the average degree ofpolymerization of the polyvinyl alcohol is 200 or more, the penetrationresistance of the interlayer film for a laminated glass can be improved.When the average degree of polymerization of the polyvinyl alcohol is5,000 or less, the formability of the different layer can be ensured.The lower limit of the average degree of polymerization of the polyvinylalcohol is more preferably 500 and the upper limit thereof is morepreferably 4,000.

The lower limit of the carbon number of an aldehyde used foracetalization of the polyvinyl alcohol is preferably 3 and the upperlimit thereof is preferably 4. When the aldehyde having 3 or more carbonatoms is used, the penetration resistance of the interlayer film for alaminated glass is improved. When the aldehyde having 4 or less carbonatoms is used, the productivity of the polyvinyl acetal Y is improved.The C3-C4 aldehyde may be a linear or branched aldehyde, and examplesthereof include n-butyraldehyde.

The upper limit of the hydroxy group content of the polyvinyl acetal Yis preferably 33 mol % and the lower limit thereof is preferably 28 mol%. When the hydroxy group content of the polyvinyl acetal Y is 33 mol %or less, whitening of the interlayer film for a laminated glass can beprevented. When the hydroxy group content of the polyvinyl acetal Y is28 mol % or more, the penetration resistance of the interlayer film fora laminated glass can be improved.

The lower limit of the acetal group content of the polyvinyl acetal Y ispreferably 60 mol % and the upper limit thereof is preferably 80 mol %.When the acetal group content is 60 mol % or more, the plasticizer in anamount needed for exhibiting sufficient penetration resistance can becontained. When the acetal group content is 80 mol % or less, theadhesiveness between the different layer and glass can be ensured. Thelower limit of the acetal group content of the polyvinyl acetal Y ismore preferably 65 mol % and the upper limit thereof is more preferably69 mol %.

The upper limit of the acetyl group content of the polyvinyl acetal Y ispreferably 7 mol %. When the acetyl group content of the polyvinylacetal Y is 7 mol % or less, the different layer has higherhydrophobicity, thereby preventing whitening. The upper limit of theacetyl group content of the polyvinyl acetal Y is more preferably 2 mol%, and the lower limit thereof is preferably 0.1 mol %.

The hydroxy group content, acetal group content, and acetyl groupcontent of the polyvinyl acetal Y can be measured by the same methods asthose described for the polyvinyl acetal X.

In order to impart heat insulation properties to the interlayer film fora laminated glass of the present invention, for example, one, two, orall of the layers constituting the multilayer structure may contain aheat ray absorber.

The heat ray absorber may be any heat ray absorber that can blockinfrared rays. Specifically, preferred is at least one selected from thegroup consisting of tin-doped indium oxide (ITO) particles,antimony-doped tin oxide (ATO) particles, aluminum-doped zinc oxide(AZO) particles, indium-doped zinc oxide (IZO) particles, tin-doped zincoxide particles, silicon-doped zinc oxide particles, lanthanumhexaboride particles, and cerium hexaboride particles.

The interlayer film for a laminated glass of the present invention mayhave any thickness. The lower limit of the thickness is preferably 50 μmand the upper limit thereof is preferably 1,700 μm. The lower limit ismore preferably 100 μm and the upper limit is more preferably 1,000 μm.The upper limit is still more preferably 900 μm. The lower limit of thethickness of the interlayer film for a laminated glass means thethickness of the thinnest portion of the interlayer film for a laminatedglass. The upper limit of the thickness of the interlayer film for alaminated glass means the thickness of the thickest portion of theinterlayer film for a laminated glass.

The interlayer film for a laminated glass of the present invention mayhave a wedge-shaped cross section. In the case where the interlayer filmfor a laminated glass has a wedge-shaped cross section, adjustment ofthe wedge angle θ of the wedge shape according to the mounting angle ofthe laminated glass can prevent occurrence of double images or ghostimages in a head-up display which allows the driver to see the frontvisual field and the meter image at the same time without turning thedriver's eyes downward. For further preventing occurrence of doubleimages, the lower limit of the wedge angle θ is preferably 0.1 mrad,more preferably 0.2 mrad, still more preferably 0.3 mrad and the upperlimit is preferably 1 mrad, more preferably 0.9 mrad.

In the case where the interlayer film for a laminated glass having awedge-shaped cross section is produced by, for example, extrusionmolding a resin composition using an extruder, the interlayer film mayhave its minimum thickness in a region slightly inward from one end onthe thinner side (specifically, a region spaced inward from one end onthe thinner side by a distance of 0X to 0.2X where X is the distancebetween the one end and the other end). The interlayer film may alsohave its maximum thickness in a region slightly inward from one end onthe thicker side (specifically, a region spaced inward from one end onthe thicker side by a distance of 0X to 0.2X where X is the distancebetween the one end and the other end). Herein, such a shape is includedin the wedge shape. The distance X between the one end and the other endof the interlayer film for a laminated glass is preferably 3 m orshorter, more preferably 2 m or shorter, particularly preferably 1.5 mor shorter and is preferably 0.5 m or longer, more preferably 0.8 m orlonger, particularly preferably 1 m or longer.

The wedge angle θ of the interlayer film for a laminated glass having awedge-shaped cross section means the interior angle at the intersectionof a straight line connecting a thickest portion and a thinnest portionon one surface of the interlayer film for a laminated glass and astraight line connecting a thickest portion and a thinnest portion onthe other surface.

In the case where the surfaces have a plurality of thickest portions orthinnest portions, in the case where the thickest portion is in theregion spaced from one end on the thicker side by a distance of 0X to0.2X, or in the case where the thinnest portion is in the region spacedfrom one end on the thinner side by a distance of 0X to 0.2X, thethickest portion and the thinnest portion are selected to maximize thewedge angle θ to be obtained.

In the case of the interlayer film for a laminated glass of the presentinvention having a wedge-shaped cross section, the interlayer film for alaminated glass preferably has a multilayer structure including onelayer and a different layer (hereafter, also referred to as a“shape-adjusting layer”). The cross-sectional shape of the entireinterlayer film for a laminated glass can be controlled to have a wedgeshape with a certain wedge angle by controlling the thickness of the onelayer to be within a certain range and stacking the shape-adjustinglayer. The shape-adjusting layer may be stacked on only one or both ofthe surfaces of the one layer. Further, multiple shape-adjusting layersmay be stacked.

The interlayer film for a laminated glass of the present invention maybe produced by any method, and a conventionally known method may beused. In an exemplary method, the thermoplastic resin is kneaded withother component(s) added as needed, and the mixture is extrusion-molded.

Any kneading method may be used. Examples of the method include a methodusing an extruder, a plastograph, a kneader, a Banbury mixer, or acalender roll.

The present invention also encompasses a laminated glass including apair of glass plates and the interlayer film for a laminated glass ofthe present invention interposed between the pair of glass plates.

The glass plates may be transparent plate glass commonly used. Examplesthereof include inorganic glass such as float plate glass, polishedplate glass, molded plate glass, wired glass, wire-reinforced plateglass, colored plate glass, heat-absorbing glass, heat-reflecting glass,and green glass. Also usable is UV light-shielding glass having a UVlight-shielding coat layer on the surface of glass. Moreover, organicplastic plates such as polyethylene terephthalate, polycarbonate, orpolyacrylate plates may also be used.

As the glass plates, two or more kinds of glass plates may be used.Exemplary cases thereof include a laminated glass in which theinterlayer film for a laminated glass of the present invention isinterposed between a transparent float plate glass and a colored glassplate such as green glass. Moreover, as the glass plates, two or morekinds of glass plates different in the thickness may be used.

The laminated glass of the present invention can be suitably produced bya vacuum deaeration method.

In the vacuum deaeration method, a laminate including an interlayer filmfor a laminated glass interposed between at least two glass plates isplaced in a rubber bag, and vacuum suctioned for removal of airremaining between the glass plates and the interlayer film so as to bepreliminarily pressure bonded. The laminate is then pressurized withheat, for example, in an autoclave for final pressure bonding to providea laminated glass.

In the interlayer film for a laminated glass of the present invention,the surface with the recesses has a texture aspect ratio Str lower thanor equal to a certain value, thus preventing preceding sealing andenabling production of a laminated glass having high visible lighttransmittance even when the deaeration for the preliminary pressurebonding and the heating for the final pressure bonding are performed inparallel in the vacuum deaeration method to shorten the processduration.

Advantageous Effects of Invention

The present invention can provide an interlayer film for a laminatedglass that enables production of a laminated glass having high visiblelight transmittance even when deaeration for preliminary pressurebonding and heating for final pressure bonding are performed in parallelin a vacuum deaeration method. The present invention also can provide amethod for producing the interlayer film for a laminated glass and alaminated glass including the interlayer film for a laminated glass.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic view illustrating an exemplary interlayer film fora laminated glass in which recesses each having a groove shape with acontinuous bottom are arranged on a surface at equal intervals andadjacent recesses are arranged side by side in parallel to each other.

FIG. 2 is a schematic view illustrating an exemplary interlayer film fora laminated glass in which recesses each having a groove shape with acontinuous bottom are arranged on a surface at equal intervals andadjacent recesses are arranged side by side in parallel to each other.

FIG. 3 is a schematic view illustrating an exemplary interlayer film fora laminated glass in which recesses each having a groove shape with acontinuous bottom are arranged on a surface at unequal intervals andadjacent recesses are arranged side by side in parallel to each other.

FIG. 4 is a schematic view explaining positions where parallel lighttransmittance Tp is measured in a laminate after preliminary pressurebonding in production of a laminated glass in examples.

DESCRIPTION OF EMBODIMENTS

Embodiments of the present invention are specifically described in thefollowing with reference to, but not limited to, examples.

Example 1 (1) Preparation of Resin Film

Polyvinyl alcohol having an average degree of polymerization of 1,700was acetalized with n-butyraldehyde to give polyvinyl butyral having anacetyl group content of 1 mol %, a butyral group content of 69 mol %,and a hydroxy group content of 30 mol %. To 100 parts by mass of theobtained polyvinyl butyral were added 39 parts by mass of a plasticizerand an adhesion modifier at a magnesium concentration in the film of 50ppm. The mixture was kneaded well with a mixing roll to give a resincomposition. The plasticizer used was triethylene glycol-diethylhexanoate (3GO). The adhesion modifier used was a 50% by mass:50%by mass mixture of magnesium bis(2-ethyl butyrate) and magnesiumacetate.

The obtained resin composition was extruded using an extruder to give asingle-layer interlayer film for a laminated glass having a thickness of760 μm.

(2) First Step

Embossing rolls having a coarse main embossed pattern and a finesub-embossed pattern were prepared by a method including forming randomprotrusions and recesses on the surfaces of iron rolls with an abrasivematerial, subjecting the iron rolls to vertical grinding, and furtherforming finer protrusions and recesses with a finer abrasive material onplanar portions after the vertical grinding. As a first step, using thepair of embossing rolls as a device for transferring a pattern ofprotrusions and recesses, a random pattern of protrusions and recesseswas transferred to both surfaces of the resin film.

The transferring conditions employed here were a temperature of theinterlayer film for a laminated glass of 80° C., a temperature of therolls of 145° C., a linear velocity of 10 m/min, a line width of 1.5 m,and a press linear pressure of 1 to 100 kN/m.

The resin film after the first step was subjected to measurements of thearithmetic average roughness Ra and the interval Sm between the recessesby methods in conformity with JIS B 0601(1994). The measurements wereperformed in an environment at a temperature of 23° C. and a humidity of30 RH % under the conditions of a cut-off value of 2.5 mm, a standardlength of 2.5 mm, a spare length of 2.5 mm, an evaluation length of 12.5mm, a tip radius of the probe of 2 μm, a tip angle of 60°, and ameasurement speed of 0.5 mm/s.

In the case where the Sm exceeds 450 μm, the measurements may beinaccurate with a standard length of 2.5 mm. In such a case, themeasurement was performed by changing the cut-off value to 8 mm orlonger.

(3) Second Step

In the second step, a pair of rolls including a metal roll having asurface milled with a triangular oblique line-type mill and a rubberroll having a JIS hardness of 65 to 75 was used as a device fortransferring a pattern of protrusions and recesses. The resin film afterthe first step was passed through the device for transferring a patternof protrusions and recesses to impart, to one surface of the resin film,protrusions and recesses in which recesses each had a groove shape witha continuous bottom (shape of an engraved line) and were arranged sideby side in parallel to each other at equal intervals. The transferringconditions employed here were a temperature of the resin film of 70° C.,a temperature of the rolls of 140° C., a linear velocity of 10 m/min,and a press linear pressure of 1 to 100 kN/m.

Subsequently, the same operations were performed on the other surface ofthe resin film to impart recesses each having a groove shape with acontinuous bottom (shape of an engraved line).

The resin film after the second step was subjected to measurements ofthe ten-point average roughness Rz, the arithmetic average roughness Ra,and the interval Sm between the recesses by methods in conformity withJIS B 0601(1994). The measurements were performed in a directionperpendicular to the groove shape with a continuous bottom in anenvironment at a temperature of 23° C. and a humidity of 30 RH % underthe conditions of a cut-off value of 2.5 mm, a standard length of 2.5mm, a spare length of 2.5 mm, an evaluation length of 12.5 mm, a tipradius of the probe of 2 μm, a tip angle of 60°, and a measurement speedof 0.5 mm/s.

In the case where the Sm exceeds 450 μm, the measurements may beinaccurate with a standard length of 2.5 mm. In such a case, themeasurement was performed by changing the cut-off value to 8 mm orlonger.

(4) Measurement of Str

The Str was measured in an environment at a temperature of 23° C. and ahumidity of 30 RH % by the following method.

A surface of the interlayer film for a laminated glass was analyzedusing a three-dimensional white light interference microscope(ContourGT-K available from Bruker AXS GmbH) in a 2 mm square field ofview at an objective lens magnification of 50 times, an internal lensmagnification of 0.5 times, and a resolution set to “half resolution” toobtain images. In this operation, the light quantity and threshold wereset as appropriate to minimize noise in the analysis. The obtainedimages were subjected to planarization and noise removal processes, andcoarse protrusions and recesses were removed using a Gaussian filter.Then, the Str value was calculated by a method specified in ISO 25178.

Analytical software “Vision64” included in the apparatus was used inimage processing. The planarization process involved the following firstto third processing operations. As the first processing, the processing“Terms Removal (F-Operator)” on Analysis Toolbox was performed under theanalysis condition “Tilt only (Plane Fit)”. As the second processing,the processing “Statistic Filter” was performed under the analysisconditions “Filter type: median” and “Filter size: 3”. As the thirdprocessing, the processing “data Restore” was performed by selecting theanalysis condition “Legacy”, selecting Restore Edge condition, andsetting Iteration condition to a value for sufficient data complement.As the noise removal processing (fourth processing), the processing“Gaussian Regression Filter” was performed under the analysis conditions“under Band pass condition, order: 0, Type: Regular, Long wavelengthcutoff: 1 mm, and Short wavelength cutoff: 0.002 mm”. At this time, theadvance setup was performed under initial conditions. The image dataafter the first processing through the fourth processing was subjectedto the fifth processing “S parameters-Spatial” under the analysiscondition “Angle resolution: 1 deg, Search range: From 0 to 90”. Theresulting “Str” was used as the Str value.

The measurement was performed on two points in the center portion of a10 cm square sample of the interlayer film for a laminated glass. Theaverage of the obtained values was used as the Str value. Otherwise themeasurement was in conformity with ISO 25178(2012).

The Str was measured on both an interlayer film for a laminated glass(before heating) not heated after production and an interlayer film fora laminated glass (after heating) heated at 100° C. for 15 minutes bythe following method.

A 5-mm-thick stainless steel plate and three 2.5-mm-thick clear glassplates were placed in a gear oven, and each plate was heated to asurface temperature of 100° C. Before heating to 100° C., the surface ofthe stainless steel plate to be in contact with the interlayer film fora laminated glass in the subsequent step was surface-treated with asilicone release agent (available from Shin-Etsu Chemical Co., Ltd.,SEPA-COAT SP). After the surface temperatures of the stainless steelplate and the clear glass plates reached 100° C., the temperature of thegear oven itself was set at 100° C. On the stainless steel plate wasplaced the interlayer film for a laminated glass cut to a size of 10cm×10 cm. On the interlayer film was placed a polyethylene terephthalate(PET) sheet cut to a frame shape having an inside dimensions of 7 cm×7cm and a thickness of 50 μm. On the PET sheet were placed the three2.5-mm-thick clear glass plates (10 cm×10 cm) heated to 100° C. Here,the interlayer film for a laminated glass and the PET sheet had beenleft to stand in an atmosphere at a temperature of 23° C. and a humidityof 30% for three hours before placed on, respectively, the stainlesssteel plate and the interlayer film for a laminated glass.

The interlayer film for a laminated glass was held in the gear oven at100° C. for 15 minutes. The interlayer film was then taken out,transferred onto a 23° C. stainless steel plate, and cooled thereon. Themeasurement of the Str was performed on the center portion on thesurface on the stainless steel side.

Examples 2 to 13 and Comparative Examples 1 to 6

An interlayer film for a laminated glass having recesses in the shape ofengraved lines on the surfaces was produced as in Example 1 except thatthe conditions for the first step and the second step were changed asshown in Table 1 or 2. The linear velocities in the first step and thesecond step were the same.

In Example 6 and Comparative Example 4, the die used for extruding aresin film through an extruder had a lip shape for a lip method.Specifically, a resin film having fine protrusions and recesses on thesurfaces was obtained using a lip die with a lip gap of 0.7 to 1.4 mm bya method in which the temperature of the resin composition at the inletof the die was adjusted to 150° C. to 270° C., the temperature of thelip die was adjusted to 210° C., the line speed was 10 m/min, and thevariation range of the inlet pressure of the extruder within 30 secondswas controlled to 0.4% or less. In Example 6 and Comparative Example 4,this operation was performed instead of the first step.

Example 14 (1) Preparation of Resin Film

Polyvinyl alcohol having an average degree of polymerization of 1,700was acetalized with n-butyraldehyde to give polyvinyl butyral having anacetyl group content of 1 mol %, a butyral group content of 69 mol %,and a hydroxy group content of 30 mol %. To 100 parts by mass of theobtained polyvinyl butyral were added 39 parts by mass of a plasticizerand an adhesion modifier at a magnesium concentration in the film of 50ppm. The mixture was kneaded well with a mixing roll to give a resincomposition.

The plasticizer used was triethylene glycol-di-2-ethylhexanoate (3GO).The adhesion modifier used was a 50% by mass:50% by mass mixture ofmagnesium bis(2-ethyl butyrate) and magnesium acetate.

The obtained resin composition was extruded through an extruder into aresin film having a wedge-shaped cross section. The obtained resin filmhad a minimum thickness at one end and a maximum thickness at the otherend, and did not have a uniform thickness portion. The distance betweenthe one end and the other end of the obtained resin film was 1 m.

An interlayer film for a laminated glass having recesses in the shape ofengraved lines on the surfaces was produced as in Example 1 except thatthe obtained resin film having a wedge-shaped cross section was used,and that the conditions for the first step and the second step werechanged as shown in Table 3. The linear velocities in the first step andthe second step were the same.

The obtained interlayer film was subjected to measurements of theminimum thickness, the maximum thickness, the cross-sectional shape, andthe wedge angle. The obtained values were shown in Table 3.

Examples 15 to 17 and Comparative Example 7

A resin film having a wedge-shaped cross section was obtained byadjusting the extruding conditions such that the minimum thickness, themaximum thickness, the cross-sectional shape, and the wedge angle of theresulting interlayer film were as shown in Table 3.

An interlayer film for a laminated glass having recesses in the shape ofengraved lines on the surfaces was produced as in Example 14 except thatthe obtained resin film having a wedge-shaped cross section was used,and that the conditions for the first step and the second step werechanged as shown in Table 3. The linear velocities in the first step andthe second step were the same.

Example 18 (1) Preparation of Composition for First Resin Layer

Polyvinyl alcohol having an average degree of polymerization of 1,700was acetalized with n-butyraldehyde to give polyvinyl butyral having anacetyl group content of 1 mol %, a butyral group content of 69 mol %,and a hydroxy group content of 30 mol %. To 100 parts by mass of theobtained polyvinyl butyral were added 36 parts by mass of a plasticizerand an adhesion modifier at a magnesium concentration in the film of 50ppm. The mixture was kneaded well with a mixing roll to give resincomposition for a first resin layer.

The plasticizer used was triethylene glycol-di-2-ethylhexanoate (3GO).The adhesion modifier used was a 50% by mass:50% by mass mixture ofmagnesium bis(2-ethyl butyrate) and magnesium acetate.

(2) Preparation of Composition for Second Resin Layer

Polyvinyl alcohol having an average degree of polymerization of 2,300was acetalized with n-butyraldehyde to give polyvinyl butyral having anacetyl group content of 12.5 mol %, a butyral group content of 64 mol %,and a hydroxy group content of 23.5 mol %. To 100 parts by mass of theobtained polyvinyl butyral were added 76.5 parts by mass of triethyleneglycol-di-2-ethylhexanoate (3GO) as a plasticizer. The mixture waskneaded well with a mixing roll to give a resin composition for a secondresin layer.

(3) Preparation of Resin Film

The obtained resin composition for a first resin layer and resincomposition for a second resin layer were co-extruded using aco-extruder to prepare a resin film having a rectangular cross sectionand a laminated structure (first resin layer/second resin layer/firstresin layer).

An interlayer film for a laminated glass having recesses in the shape ofengraved lines on the surfaces was produced as in Example 1 except thatthe obtained resin film having a rectangular cross section was used, andthat the conditions for the first step and the second step were changedas shown in Table 4. The linear velocities in the first step and thesecond step were the same.

The obtained interlayer film was subjected to measurements of theaverage thicknesses of the first resin layer, the second resin layer,and the interlayer film. The obtained values were shown in Table 4.

Examples 19 to 23 and Comparative Example 8

A resin composition for a first resin layer and a resin composition fora second resin layer were prepared by changing the amounts of thepolyvinyl butyral and plasticizer as shown in Table 4. A resin filmhaving a rectangular cross section and a laminated structure (firstresin layer/second resin layer/first resin layer) was prepared byadjusting the co-extruding conditions such that the average thicknessesof the first resin layer, the second resin layer, and the interlayerfilm were as shown in Table 4.

An interlayer film for a laminated glass having recesses in the shape ofengraved lines on the surfaces was produced as in Example 18 except thatthe obtained resin film having a rectangular cross-section was used, andthat the conditions for the first step and the second step were changedas shown in Table 4. The linear velocities in the first step and thesecond step were the same.

Example 24 (1) Preparation of Composition for First Resin Layer

Polyvinyl alcohol having an average degree of polymerization of 1,700was acetalized with n-butyraldehyde to give polyvinyl butyral having anacetyl group content of 1 mol %, a butyral group content of 69 mol %,and a hydroxy group content of 30 mol %. To 100 parts by mass of theobtained polyvinyl butyral were added 36.0 parts by mass of aplasticizer and an adhesion modifier at a magnesium concentration in thefilm of 50 ppm. The mixture was kneaded well with a mixing roll toprovide a resin composition for a first resin layer.

The plasticizer used was triethylene glycol-di-2-ethylhexanoate (3GO).The adhesion modifier used was a 50% by mass:50% by mass mixture ofmagnesium bis(2-ethyl butyrate) and magnesium acetate.

(2) Preparation of Composition for Second Resin Layer

Polyvinyl alcohol having an average degree of polymerization of 2,300was acetalized with n-butyraldehyde to give polyvinyl butyral having anacetyl group content of 12.5 mol %, a butyral group content of 64 mol %,and a hydroxy group content of 23.5 mol %. To 100 parts by mass of theobtained polyvinyl butyral were added 76.5 parts by mass of triethyleneglycol-di-2-ethylhexanoate (3GO) as a plasticizer. The mixture waskneaded well with a mixing roll to give a resin composition for a secondresin layer.

(3) Preparation of Resin Film

The obtained resin composition for a first resin layer and resincomposition for a second resin layer were co-extruded using aco-extruder to prepare a resin film having a wedge-shaped cross sectionand a laminated structure (first resin layer/second resin layer/firstresin layer). The obtained resin film having a wedge-shaped crosssection had a minimum thickness at one end and a maximum thickness atthe other end, and did not have a uniform thickness portion. Thedistance between the one end and the other end of the obtainedinterlayer film having a wedge-shaped cross section was 1 m.

An interlayer film for a laminated glass having recesses in the shape ofengraved lines on the surfaces was produced as in Example 1 except thatthe obtained resin film having a wedge-shaped cross section was used,and that the conditions for the first step and the second step werechanged as shown in Table 5. The linear velocities in the first step andthe second step were the same.

The obtained interlayer film was subjected to measurements of theminimum thickness, the maximum thickness, the cross-sectional shape, andthe wedge angle of the first resin layer, the second resin layer, andthe interlayer film. The obtained values were shown in Table 5.

Comparative Example 9

A resin composition for a first resin layer and a resin composition fora second resin layer were prepared by changing the amounts of thepolyvinyl butyral and plasticizer as shown in Table 5. A resin filmhaving a wedge-shaped cross section and a laminated structure (firstresin layer/second resin layer/first resin layer) was prepared byadjusting the co-extruding conditions such that the minimum thickness,the maximum thickness, the cross-sectional shape, and the wedge angle ofthe first resin layer, the second resin layer, and the interlayer filmwere as shown in Table 5.

An interlayer film for a laminated glass having recesses in the shape ofengraved lines on the surfaces was produced as in Example 24 except thatthe obtained resin film having a wedge-shaped cross section was used,and that the conditions for the first step and the second step werechanged as shown in Table 5. The linear velocities in the first step andthe second step were the same.

(Evaluation)

The interlayer films for a laminated glass and laminated glassesobtained in the examples and comparative examples were evaluated by thefollowing methods.

Tables 1 to 5 show the results.

(1) Evaluation of Deaeration Properties (23° C. to 90° C.) For Examples1 to 13, Comparative Examples 1 to 6, Examples 18 to 23, and ComparativeExample 8, the obtained interlayer film for a laminated glass wasinterposed between two clear glass plates (15 cm in length×15 cm inwidth×2.5 mm in thickness), and the interlayer film portions protrudingfrom the laminate were cut to prepare a laminate for evaluation.

For Examples 14 to 17, Comparative Example 7, Example 24, andComparative Example 9, the interlayer film for a laminated glass wasinterposed between two clear glass plates such that the one end havingthe minimum thickness of the interlayer film for a laminated glass wasincluded in the laminate, and that one end of each clear glass plate wasaligned with the end having the minimum thickness of the interlayer filmfor a laminated glass. The interlayer film portions protruding from thelaminate were cut to prepare a laminate for evaluating the thinnestportion. Separately, the interlayer film for a laminated glass wasinterposed between two glass plates such that the one end having themaximum thickness of the interlayer film for a laminated glass wasincluded in the laminate, and that one end of each clear glass plateswas aligned with the end having the maximum thickness of the interlayerfilm for a laminated glass. The interlayer film portions protruding fromthe laminate were cut to prepare a laminate for evaluating the thickestportion.

Since the interlayer films for a laminated glass having a wedge-shapedcross section produced in the examples and comparative examples of thepresent application had the minimum thickness at one end and the maximumthickness at the other end, the laminates for evaluating the thinnestportion and the laminates for evaluating the thickest portion wereprepared by the above process. In the case of an interlayer film for alaminated glass having the minimum thickness and the maximum thicknessat portions other than the ends, the laminate for evaluating thethinnest portion and the laminate for evaluating the thickest portionare preferably produced such that the portion having the minimumthickness and the portion having the maximum thickness are positioned inthe middle of the clear glass plates. When it is difficult to positionthe portion having the minimum thickness and the portion having themaximum thickness in the middle of the clear glass plates, the laminatefor evaluating the thinnest portion and the laminate for evaluating thethickest portion may be produced by the above process such that one endof each clear glass plate was aligned with one end of the interlayerfilm for a laminated glass.

The obtained laminate for evaluation, laminate for evaluating thethinnest portion, and laminate for evaluating the thickest portion wereeach stored at 23° C. and 30 RH % until the surface temperature of theglass reached 23° C. The laminate was then transferred into a rubberbag. The rubber bag was connected to a vacuum suction device, andheating and depressurization were simultaneously performed to heat thelaminate under reduced pressure of −600 mmHg such that the surfacetemperature of the glass of the laminate (preliminary pressure bondingtemperature) reached 90° C. after 14 minutes. Thereafter, the laminatewas cooled until the surface temperature of the glass of the laminatereached 40° C., and then the pressure was returned to atmosphericpressure to complete the preliminary pressure bonding.

The preliminary pressure-bonded laminate was put in an autoclave andheld under the conditions of a temperature of 140° C. and a pressure of1,300 kPa for 10 minutes. The temperature was then lowered to 50° C. andthe pressure was returned to atmospheric pressure to complete the finalpressure bonding. A laminated glass was thus obtained.

The parallel light transmittance Tp (%) of the laminate after thepreliminarily pressure bonding in the production of the laminated glasswas measured with a haze meter (HM-150 available from Murakami ColorResearch Laboratory) in conformity with JIS K 7105.

FIG. 4 is a schematic view explaining positions where the parallel lighttransmittance Tp is measured. With respect to the laminate of 15 cm inlength×15 cm in width, the parallel light transmittance was measured atfive points (the points surrounded by dotted lines in FIG. 4 ): thecenter at which two diagonals of the laminate intersect; and four points5.6 cm away in the diagonal direction from the apexes of the laminate.The average of the measured values was taken as the parallel lighttransmittance Tp.

Reduction in transparency of the laminated glass is caused by defectivedeaeration during preliminary pressure bonding. Accordingly, thedeaeration properties of the interlayer film for a laminated glass canbe evaluated more precisely by measurement of the parallel lighttransmittance of the laminate after preliminarily pressure bonding thananalysis of foaming in the laminated glass.

For use in applications such as automotive windshields, the parallellight transmittance Tp needs to be at least 56%.

(2) Evaluation of Deaeration Properties (50° C. to 90° C.)

A laminate for evaluation, a laminate for evaluating the thinnestportion, and a laminate for evaluating the thickest portion wereobtained as in the evaluation of deaeration properties (23° C. to 90°C.)

The obtained laminate for evaluation, laminate for evaluating thethinnest portion, and laminate for evaluating the thickest portion wereeach stored in a gear oven until the surface temperature of the glassreached 50° C. The laminate was then transferred into a rubber bagpreheated to 50° C., and stored therein for three minutes. The rubberbag was then connected to a vacuum suction device to performdepressurization. The laminate was heated under reduced pressure of −600mmHg such that the surface temperature of the glass of the laminate(preliminary pressure bonding temperature) reached 90° C. after 14minutes. Thereafter, the laminate was cooled until the surfacetemperature of the glass of the laminate reached 40° C., and then thepressure was returned to atmospheric pressure to complete thepreliminary pressure bonding.

The preliminary pressure-bonded laminate was put in an autoclave andstored under the conditions of a temperature of 140° C. and a pressureof 1,300 kPa for 10 minutes. The temperature was then lowered to 50° C.and the pressure was returned to atmospheric pressure to complete thefinal pressure bonding. A laminated glass was thus obtained.

The parallel light transmittance Tp (%) of the laminate after thepreliminary pressure bonding in the production of the laminated glasswas measured in the same manner as above.

TABLE 1 Example 1 Example 2 Example 3 Example 4 Example 5 ProductionFirst Impartment of protrusions and Roll Roll Roll Roll Roll steprecesses embossment embossment embossment embossment embossment First Ra(μm) 2.8 1.0 1.1 1.3 1.5 surface Sm (μm) 460 660 650 580 650 Ra × Sm1288 660 715 754 975 Second Ra (μm) 2.9 1.1 0.9 1.5 1.4 surface Sm (μm)500 640 600 600 600 Ra × Sm 1450 704 540 900 840 Second Impartment ofprotrusions and Roll Roll Roll Roll Roll step recesses embossmentembossment embossment embossment embossment Linear velocity (m/min) 1010 10 10 10 Interlayer First Recess shape Engraved lines Engraved linesEngraved lines Engraved lines Engraved lines film for surface Rz (μm) 4542 30 31 45 laminated Sm (μm) 300 295 301 200 196 glass Str (beforeheating) 0.037 0.032 0.035 0.020 0.030 Str (after heating) 0.071 0.0400.040 0.030 0.033 ΔStr 0.034 0.008 0.005 0.010 0.003 Second Recess shapeEngraved lines Engraved lines Engraved lines Engraved lines Engravedlines surface Rz (μm) 45 43 28 30 45 Sm (μm) 300 295 300 200 199 Str(before heating) 0.034 0.030 0.037 0.022 0.030 Str (after heating) 0.0710.039 0.042 0.032 0.033 ΔStr 0.037 0.009 0.005 0.010 0.003 Evaluation ofTp (23° C. to 90° C.) (%) 65 71 66 75 72 deaeration Tp (50 to 90° C.)(%) 60 65 60 64 62 properties Example 6 Example 7 Example 8 Example 9Production First Impartment of protrusions and Melt fracture Roll RollRoll step recesses embossment embossment embossment First Ra (μm) 2.51.6 3.5 3.5 surface Sm (μm) 350 650 520 520 Ra × Sm 875 1040 1820 1820Second Ra (μm) 2.4 1.5 3.6 3.6 surface Sm (μm) 360 640 550 550 Ra × Sm864 960 1980 1820 Second Impartment of protrusions and Roll Roll RollRoll step recesses embossment embossment embossment embossment Linearvelocity (m/min) 10 10 5 8 Interlayer First Recess shape Engraved linesEngraved lines Engraved lines Engraved lines film for surface Rz (μm) 4039 43 43 laminated Sm (μm) 199 200 195 202 glass Str (before heating)0.028 0.021 0.026 0.029 Str (after heating) 0.039 0.027 0.030 0.045 ΔStr0.011 0.006 0.004 0.016 Second Recess shape Engraved lines Engravedlines Engraved lines Engraved lines surface Rz (μm) 37 38 42 43 Sm (μm)199 200 200 197 Str (before heating) 0.030 0.022 0.028 0.030 Str (afterheating) 0.039 0.028 0.031 0.045 ΔStr 0.009 0.006 0.003 0.015 Evaluationof Tp (23° C. to 90° C.) (%) 74 75 70 68 deaeration Tp (50 to 90° C.)(%) 63 73 63 59 properties

TABLE 2 Comparative Example 10 Example 11 Example 12 Example 13 Example1 Production First Impartment of protrusions and Roll Roll Roll RollRoll step recesses embossment embossment embossment embossmentembossment First Ra (μm) 3.5 0.9 1.8 1.5 6.0 surface Sm (μm) 520 590 600150 520 Ra × Sm 1820 531 1080 225 3120 Second Ra (μm) 3.7 0.9 1.9 1.66.2 surface Sm (μm) 450 550 550 150 510 Ra × Sm 1665 495 1045 240 3162Second Impartment of protrusions and Roll Roll Roll Roll Roll steprecesses embossment embossment embossment embossment embossment Linearvelocity (m/min) 10 10 10 10 10 Interlayer First Recess shape Engravedlines Engraved lines Engraved lines Engraved lines Engraved lines filmfor surface Rz (μm) 42 35 30 38 46 laminated Sm (μm) 195 194 450 190 307glass Str (before heating) 0.029 0.015 0.035 0.022 0.060 Str (afterheating) 0.060 0.020 0.043 0.022 0.105 ΔStr 0.031 0.005 0.008 0.0000.045 Second Recess shape Engraved lines Engraved lines Engraved linesEngraved lines Engraved lines surface Rz (μm) 38 38 33 36 45 Sm (μm) 203192 450 190 300 Str (before heating) 0.035 0.015 0.035 0.022 0.060 Str(after heating) 0.065 0.018 0.045 0.023 0.100 ΔStr 0.030 0.003 0.0100.001 0.040 Evaluation of Tp (23° C. to 90° C.) (%) 66 77 65 75 64deaeration Tp (50 to 90° C.) (%) 57 75 57 73 49 properties ComparativeComparative Comparative Comparative Comparative Example 2 Example 3Example 4 Example 5 Example 6 Production First Impartment of protrusionsand Roll Roll Melt fracture Roll Roll step recesses embossmentembossment embossment embossment First Ra (μm) 7.0 6.0 8.0 6.0 3.0surface Sm (μm) 620 450 430 450 480 Ra × Sm 4340 2700 3440 2700 1440Second Ra (μm) 6.7 5.8 8.5 5.5 3.3 surface Sm (μm) 650 470 470 450 460Ra × Sm 4355 2726 3995 2475 1518 Second Impartment of protrusions andRoll Roll Roll Roll Roll step recesses embossment embossment embossmentembossment embossment Linear velocity (m/min) 10 10 10 20 20 InterlayerFirst Recess shape Engraved lines Engraved lines Engraved lines Engravedlines Engraved lines film for surface Rz (μm) 42 30 40 30 38 laminatedSm (μm) 400 200 200 200 195 glass Str (before heating) 0.070 0.045 0.0500.045 0.042 Str (after heating) 0.250 0.092 0.300 0.220 0.150 ΔStr 0.1800.047 0.250 0.175 0.031 Second Recess shape Engraved lines Engravedlines Engraved lines Engraved lines Engraved lines surface Rz (μm) 40 3040 35 35 Sm (μm) 410 190 200 200 203 Str (before heating) 0.070 0.0450.060 0.043 0.044 Str (after heating) 0.270 0.095 0.320 0.200 0.160 ΔStr0.200 0.050 0.260 0.157 0.030 Evaluation of Tp (23° C. to 90° C.) (%) 6264 63 66 65 deaeration Tp (50 to 90° C.) (%) 38 52 40 43 48 properties

TABLE 3 Comparative Example 14 Example 15 Example 16 Example 17 Example7 Production First Impartment of protrusions and Roll Roll Melt fractureMelt fracture Roll step recesses embossment embossment embossment FirstRa (μm) 1.3 1.5 2.5 2.5 6.0 surface Sm (μm) 580 150 350 350 450 Ra × Sm754 225 875 875 2700 Second Ra (μm) 1.5 1.6 2.4 2.4 5.8 surface Sm (μm)600 150 360 360 470 Ra × Sm 900 240 864 864 2726 Second Impartment ofprotrusions and Roll Roll Roll Roll Roll step recesses embossmentembossment embossment embossment embossment Linear velocity (m/min) 1010 10 10 10 Interlayer Thickest First Recess shape Engraved linesEngraved lines Engraved lines Engraved lines Engraved lines film forportion surface Rz (μm) 31 38 40 40 30 laminated Sm (μm) 200 190 199 199200 glass Str (before heating) 0.020 0.022 0.028 0.028 0.050 Str (afterheating) 0.030 0.022 0.039 0.039 0.092 ΔStr 0.010 0.000 0.011 0.0110.042 Second Recess shape Engraved lines Engraved lines Engraved linesEngraved lines Engraved lines surface Rz (μm) 30 36 37 37 30 Sm (μm) 200190 199 199 190 Str (before heating) 0.022 0.022 0.030 0.030 0.050 Str(after heating) 0.032 0.023 0.039 0.039 0.095 ΔStr 0.010 0.001 0.0090.009 0.045 Thinnest First Recess shape Engraved lines Engraved linesEngraved lines Engraved lines Engraved lines portion surface Rz (μm) 3138 40 48 30 Sm (μm) 200 190 199 200 200 Str (before heating) 0.020 0.0220.028 0.025 0.050 Str (after heating) 0.030 0.022 0.039 0.030 0.092 ΔStr0.010 0.000 0.011 0.005 0.042 Second Recess shape Engraved linesEngraved lines Engraved lines Engraved lines Engraved lines surface Rz(μm) 30 36 37 37 30 Sm (μm) 200 190 199 199 190 Str (before heating)0.022 0.022 0.030 0.030 0.050 Str (after heating) 0.032 0.023 0.0390.039 0.095 ΔStr 0.010 0.001 0.009 0.009 0.045 Thickness Minimum [um]800 830 780 900 800 thickness Maximum [um] 1200 1600 1250 1230 1200thickness Cross-sectional [—] Wedge shape Wedge shape Wedge shape Wedgeshape Wedge shape shape Width mm 1000 1000 1000 1000 1000 Wedge angle[mrad] 0.40 0.77 0.47 0.33 0.40 Evaluation of Thickest Tp (23° C. to 90°C.) (%) 72 75 69 73 60 deaeration portion Tp (50 to 90° C.) (%) 60 71 5868 49 properties Thinnest Tp (23° C. to 90° C.) (%) 77 78 74 74 64portion Tp (50 to 90° C.) (%) 65 74 62 62 52

TABLE 4 Example 18 Example 19 Example 20 Example 21 First resinPolyvinyl Butyral group content [mol %] 69 68.5 69.9 69 layer butyralHydroxy group content [mol %] 30 31 29 30 resin Acetyl group content[mol %] 1 0.5 1.1 1 Amount [phr] 100 100 100 100 Plasticizer Type [—]3GO 3GO 3GO 3GO Amount [phr] 36.0 36.0 39.0 36.0 Structure Averagethickness [μm] 350 350 345 350 Cross-sectional shape [—] RectangularRectangular Rectangular Rectangular shape shape shape shape SecondPolyvinyl Butyral group content [mol %] 64 67 77.8 69 resin layerbutyral Hydroxy group content [mol %] 23.5 25.0 20.7 18.0 resin Acetylgroup content [mol %] 12.5 8 1.5 13 Amount [phr] 100 100 100 100Plasticizer Type [—] 3GO 3GO 3GO 3GO Amount [phr] 76.5 75.0 79.2 78.0Structure Average thickness [μm] 100 110 120 100 Cross-sectional shape[—] Rectangular Rectangular Rectangular Rectangular shape shape shapeshape Production First step Impartment of protrusions and recesses RollRoll Roll Roll embossment embossment embossment embossment First surfaceRa (μm) 1.4 1.4 1.4 1.8 Sm (μm) 570 580 600 610 Ra × Sm 798 812 840 1098Second surface Ra (μm) 1.6 1.6 1.6 2.0 Sm (μm) 550 550 540 550 Ra × Sm880 880 864 1100 Second Impartment of protrusions and recesses Roll RollRoll Roll step embossment embossment embossment embossment Linearvelocity (m/min) 10 10 10 10 Interlayer First surface Recess shapeEngraved lines Engraved lines Engraved lines Engraved lines film for Rz(μm) 31 31 31 30 laminated Sm (μm) 200 200 199 450 glass Str (beforeheating) 0.021 0.021 0.020 0.036 Str (after heating) 0.031 0.030 0.0300.043 ΔStr 0.010 0.009 0.010 0.007 Second surface Recess shape Engravedlines Engraved lines Engraved lines Engraved lines Rz (μm) 30 30 30 33Sm (μm) 202 200 195 450 Str (before heating) 0.022 0.021 0.022 0.036 Str(after heating) 0.032 0.031 0.032 0.046 ΔStr 0.010 0.010 0.010 0.010Structure [—] First resin First resin First resin First resinlayer/second layer/second layer/second layer/second resin layer/firstresin layer/first resin layer/first resin layer/first resin layer resinlayer resin layer resin layer Cross-sectional shape [—] RectangularRectangular Rectangular Rectangular shape shape shape shape Evaluationof Tp (23° C. to 90° C.) (%) 77 76 71 65 deaeration Tp (50 to 90° C.)(%) 65 66 61 57 properties Comparative Example 22 Example 23 Example 8First resin Polyvinyl Butyral group content [mol %] 69 69 69 layerbutyral Hydroxy group content [mol %] 30 30 30 resin Acetyl groupcontent [mol %] 1 1 1 Amount [phr] 100 100 100 Plasticizer Type [—] 3GO3GO 3GO Amount [phr] 36.0 36.0 36.0 Structure Average thickness [μm] 350350 350 Cross-sectional shape [—] Rectangular Rectangular Rectangularshape shape shape Second Polyvinyl Butyral group content [mol %] 69 6464 resin layer butyral Hydroxy group content [mol %] 18.0 23.5 23.5resin Acetyl group content [mol %] 13 12.5 12.5 Amount [phr] 100 100 100Plasticizer Type [—] 3GO 3GO 3GO Amount [phr] 78.0 76.5 76.5 StructureAverage thickness [μm] 100 100 100 Cross-sectional shape [—] RectangularRectangular Rectangular shape shape shape Production First stepImpartment of protrusions and recesses Roll Melt fracture Rollembossment embossment First surface Ra (μm) 1.8 2.7 7.2 Sm (μm) 610 340620 Ra × Sm 1098 918 4464 Second surface Ra (μm) 2.0 2.5 6.9 Sm (μm) 550360 650 Ra × Sm 1100 900 4485 Second Impartment of protrusions andrecesses Roll Roll Roll step embossment embossment embossment Linearvelocity (m/min) 10 10 10 Interlayer First surface Recess shape Engravedlines Engraved lines Engraved lines film for Rz (μm) 37 39 43 laminatedSm (μm) 192 199 402 glass Str (before heating) 0.022 0.028 0.072 Str(after heating) 0.022 0.040 0.255 ΔStr 0.000 0.012 0.183 Second surfaceRecess shape Engraved lines Engraved lines Engraved lines Rz (μm) 38 3941 Sm (μm) 190 202 405 Str (before heating) 0.021 0.030 0.075 Str (afterheating) 0.022 0.039 0.278 ΔStr 0.001 0.009 0.203 Structure [—] Firstresin First resin First resin layer/second layer/second layer/secondresin layer/first resin layer/first resin layer/first resin layer resinlayer resin layer Cross-sectional shape [—] Rectangular RectangularRectangular shape shape shape Evaluation of Tp (23° C. to 90° C.) (%) 7874 62 deaeration Tp (50 to 90° C.) (%) 74 62 38 properties

TABLE 5 Comparative Example 24 Example 9 First resin Polyvinyl Butyralgroup content [mol %] 69 69.9 layer butyral Hydroxy group content [mol%] 30 29 resin Acetyl group content [mol %] 1 1.1 Amount [phr] 100.0100.0 Plasticizer Type [—] 3GO 3GO Amount [phr] 36.0 39.0 StructureMinimum thickness [μm] 350 345 Maximum thickness [μm] 610 605Cross-sectional shape [—] Wedge Wedge Second Polyvinyl Butyral groupcontent [mol %] 64 77.8 resin layer butyral Hydroxy group content [mol%] 23.5 20.7 resin Acetyl group content [mol %] 12.5 1.5 Amount [phr]100 100 Plasticizer Type [—] 3GO 3GO Amount [phr] 76.5 79.2 StructureMinimum thickness [μm] 100 110 Maximum thickness [μm] 180 190Cross-sectional shape [—] Wedge Wedge Production First Impartment ofprotrusions and recesses Roll embossment Roll embossment step Firstsurface Ra (μm) 1.3 6.0 Sm (μm) 580.0 450 Ra × Sm 755 2700 Secondsurface Ra (μm) 2 5.8 Sm (μm) 600.0 470 Ra × Sm 900 2726 SecondImpartment of protrusions and recesses Roll embossment Roll embossmentstep Linear velocity (m/min) 10 10 Interlayer Thickest First surfaceRecess shape Engraved lines Engraved lines film for portion Rz (μm) 3130 laminated Sm (μm) 200 200 glass Str (before heating) 0.020 0.050 Str(after heating) 0.030 0.092 ΔStr 0.010 0.042 Second surface Recess shapeEngraved lines Engraved lines Rz (μm) 30 30 Sm (μm) 200 190 Str (beforeheating) 0.022 0.050 Str (after heating) 0.032 0.095 ΔStr 0.010 0.045Thinnest First surface Recess shape Engraved lines Engraved linesportion Rz (μm) 31 30 Sm (μm) 200 200 Str (before heating) 0.020 0.050Str (after heating) 0.030 0.092 ΔStr 0.010 0.042 Second surface Recessshape Engraved lines Engraved lines Rz (μm) 30 30 Sm (μm) 200 190 Str(before heating) 0.022 0.050 Str (after heating) 0.032 0.095 ΔStr 0.0100.045 Thickness Minimum thickness [—] 800 800 Maximum thickness [—] 14001400 Cross-sectional shape [—] Wedge Wedge Width mm 1000 1000 Structure[—] First resin First resin layer/second resin layer/second resinlayer/first resin layer layer/first resin layer Wedge angle [mrad] 0.600.60 Evaluation Thickest Tp (23° C. to 90° C.) (%) 70 59 of portion Tp(50 to 90° C.) (%) 60 48 deaeration Thinnest Tp (23° C. to 90° C.) (%)75 64 properties portion Tp (50 to 90° C.) (%) 64 52

INDUSTRIAL APPLICABILITY

The present invention can provide an interlayer film for a laminatedglass that enables production of a laminated glass having high visiblelight transmittance even when deaeration for preliminary pressurebonding and heating for final pressure bonding are performed in parallelin a vacuum deaeration method. The present invention also can provide amethod for producing the interlayer film for a laminated glass and alaminated glass including the interlayer film for a laminated glass.

REFERENCE SIGNS LIST

-   1 recess-   2 recess-   3 recess-   4 laminate after preliminary pressure bonding in production-   of laminated glass-   A interval between recess 1 and recess 2-   B interval between recess 1 and recess 3

1-4. (canceled)
 5. An interlayer film for a laminated glass having amultitude of recesses on at least one surface, the surface with therecesses having a ΔStr of 0.1 or less, where the ΔStr is an absolutevalue of a difference between a texture aspect ratio Str as measured inconformity with ISO 25178 and a texture aspect ratio Str as measuredafter heating at 100° C. for 15 minutes. 6-8. (canceled)
 9. A laminatedglass comprising: a pair of glass plates; and the interlayer film for alaminated glass according to claim 5 interposed between the pair ofglass plates.
 10. A method for producing the interlayer film for alaminated glass according to claim 5, comprising: a first step ofimparting fine protrusions and recesses to a surface of a resin film;and a second step of imparting recesses in the shape of engraved linesto the surface of the resin film, the resin film after the first stephaving an arithmetic average roughness Ra of 4 μm or less as measured inconformity with JIS B 0601(1994), in the second step, the recesses inthe shape of engraved lines being imparted at a linear velocity of 10m/min or less.
 11. The method for producing an interlayer film for alaminated glass according to claim 10, wherein a product (Ra×Sm) of thearithmetic average roughness Ra of the resin film after the first stepas measured in conformity with JIS B 0601(1994) and an interval Sm ofthe recesses is 2,500 or less.